Sodium/water combustion and the chemistry of wastage at sodium/water leak sites

Abstract The ignition and combustion of sodium in water vapour are demonstrated experimentally, and the composition and temperature of the flame region are discussed in terms of thermodynamic and kinetic factors. Steels have been shown to suffer rapid wastage in these flame regions. Corrosion tests to simulate the chemical environment of the flame showed that a greater rate of attack on 2.25C-1 Mo steel occurred with sodium hydroxide in a water vapour atmosphere than with sodium hydroxide alone. Extrapolation of these corrosion rates to the steel temperature in the flame leads to the conclusion that these corrosion processes are the origin of the flame wastage. The tube wastage found during water injection tests in fast reactor heat exchangers is discussed in terms of rapid corrosion by sodium hydroxide and water vapour within the flame region generated at the boundary of the water jet.